Mark signed zones with a padlock, and name clients in statistics

The zones list shows a padlock after signed zones, linking to their
DNSSEC tab. Client lists in the statistics show the host name Jarl's
records have for each address (PTR, else A/AAAA); no DNS queries.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/clientnames_test.go

@@ -0,0 +1,38 @@
+package server
+
+import (
+	"net/netip"
+	"testing"
+
+	"jarl/internal/model"
+)
+
+func TestClientNames(t *testing.T) {
+	st := model.NewState()
+	add := func(id int64, name, typ, data string, disabled bool) {
+		st.Records[id] = &model.Record{ID: id, ZoneID: 1, Name: name, Type: typ, Data: data, Disabled: disabled}
+	}
+	add(1, "nas.adbraun.lol.", "A", "192.168.1.20", false)
+	add(2, "20.1.168.192.in-addr.arpa.", "PTR", "storage.adbraun.lol.", false) // PTR wins over A
+	add(3, "web.adbraun.lol.", "A", "192.168.1.30", false)                     // no PTR: the A record's name
+	add(4, "alias.adbraun.lol.", "A", "192.168.1.30", false)                   // first in name order wins
+	add(5, "old.adbraun.lol.", "A", "192.168.1.40", true)                      // disabled: ignored
+	add(6, "secret.adbraun.lol.", "A", "192.168.1.50", false)                  // not readable
+	add(7, "v6.adbraun.lol.", "AAAA", "2001:db8::7", false)
+	add(8, "printer.adbraun.lol.", "A", "192.168.1.60", false) // not asked for
+
+	want := map[netip.Addr]bool{}
+	for _, a := range []string{"192.168.1.20", "192.168.1.30", "192.168.1.40", "192.168.1.50", "2001:db8::7", "10.0.0.1"} {
+		want[netip.MustParseAddr(a)] = true
+	}
+	got := clientNames(st, want, func(r *model.Record) bool { return r.ID != 6 })
+	exp := map[string]string{"192.168.1.20": "storage.adbraun.lol", "192.168.1.30": "alias.adbraun.lol", "2001:db8::7": "v6.adbraun.lol"}
+	if len(got) != len(exp) {
+		t.Errorf("got %v", got)
+	}
+	for a, n := range exp {
+		if got[netip.MustParseAddr(a)] != n {
+			t.Errorf("%s = %q, want %q", a, got[netip.MustParseAddr(a)], n)
+		}
+	}
+}